Hepatitis C virus (HCV) is an example of a Flaviviridae virus and is the principal etiological agent of post-transfusion and community-acquired non-A non-B hepatitis worldwide. It is estimated that over 150 million people worldwide are infected by the virus. A high percentage of carriers become chronically infected with this pathogen and many patients progress to a state of chronic liver disease, so-called chronic hepatitis C. This group is in turn at high risk for serious liver disease such as liver cirrhosis, hepatocellular carcinoma and terminal liver disease leading to death.
HCV is an enveloped positive strand RNA virus. The single strand HCV RNA genome is approximately 9500 nucleotides in length and has a single open reading frame (ORF) encoding a single large polyprotein of about 3000 amino acids. In infected cells, this polyprotein is cleaved at multiple sites by cellular and viral proteases to produce structural and non-structural (NS) proteins. In the case of HCV, the generation of mature nonstructural proteins (NS2, NS3, NS4A, NS4B, NS5A, and NS5B) is effected by two viral proteases. The first one is a metalloprotease located in NS2 that cleaves the NS2-NS3 junction in cis; the second one is a serine protease contained within the N-terminal region of NS3 (henceforth referred to as NS3 protease) and mediates all the subsequent cleavages downstream of NS3, both in cis, at the NS3-NS4A cleavage site, and in trans, at the remaining NS4A-NS4B, NS4B-NS5A, NS5A-NS5B sites. The NS4A protein appears to serve multiple functions, acting as a cofactor for the NS3 protease and possibly assisting in the membrane localization of NS3 and other viral replicase components.
The mechanism by which HCV establishes viral persistence and causes a high rate of chronic liver disease has not been elucidated. Antiviral interventions to date have focused upon, for example, ribavirin and interferon-alpha (IFN-α)-based monotherapy and combination therapy. However, not all patients are responsive to these therapies.
As such, a great need exists for identifying anti-HCV agents, and methods for combating HCV infections. The described invention meets this, and other, needs.
Literature
Literature of interest includes: Hugle et al, 2001 Virology 284:70-81; Gorbalenya and Koonin 1989 Nucleic Acids Res 17:8413-8440; Bartenschlager and Lohmann 2000 Virology 81 Pt 7:1631-1648; Reed and Rice 2000 Current Topics in Microbiology and Immunology 242:55-84; Mirzayan and Wimmer 1992 Virology 189:547-555; Rodriguez and Carrasco 1993 J. Biol Chem 268:8105-8110; and Piccininni 2002 J. Biol Chem 277:45670-45679; and published patent applications US20030087873, US20020147160 and WO99/01582.